Engine assembly including crankshaft for v4 arrangement

ABSTRACT

An engine assembly may include an engine structure and a crankshaft. The engine structure may include an engine block defining a first bank of cylinders defining two cylinders and a second bank of cylinders defining two cylinders forming a V4 arrangement. The crankshaft may include a first crank pin, a second crank pin, a third crank pin and a fourth crank. The fourth crank pin may be rotationally offset from the first crank pin by a first angle of less than two hundred and seventy degrees in the rotational direction of the crankshaft. The second and third crank pins may be located rotationally between the first crank pin and the fourth crank pin in the rotational direction.

FIELD

The present disclosure relates to engine crankshafts.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Four cylinder engines may typically incorporate the use of one or morebalance shafts to accommodate an imbalance created by the crankshaft,connecting rod and piston assembly. Additionally, operating a fourcylinder engine in a mode where one of the cylinders is temporarilydisabled for three cylinder operation may typically result in a firingperiod that is different than four cylinder operation.

SUMMARY

An engine assembly may include an engine structure and a crankshaft. Theengine structure may include an engine block defining a first bank ofcylinders defining two cylinders and a second bank of cylinders definingtwo cylinders forming a V4 arrangement. The crankshaft may include afirst crank pin, a second crank pin, a third crank pin and a fourthcrank pin. The fourth crank pin may be rotationally offset from thefirst crank pin by a first angle of less than two hundred and seventydegrees in the rotational direction of the crankshaft. The second andthird crank pins may be located rotationally between the first crank pinand the fourth crank pin in the rotational direction.

In another arrangement, an engine assembly may include an enginestructure, a crankshaft, and pistons. The engine structure may includean engine block defining a first bank of cylinders defining twocylinders and a second bank of cylinders defining two cylinders forminga V4 arrangement having a bank angle of sixty degrees. The crankshaftmay be rotationally supported on the engine structure and may include afirst crank pin, a second crank pin, a third crank pin and a fourthcrank pin. The second crank pin may be rotationally offset from thefirst crank pin in a rotational direction of the crankshaft by sixtydegrees, the third crank pin may be rotationally offset from the secondcrank pin in the rotational direction by sixty degrees, and the fourthcrank pin may be rotationally offset from the third crank pin in therotational direction by sixty degrees. A first piston may be coupled tothe first crank pin and located in the first cylinder, a second pistonmay be coupled to the second crank pin and located in the secondcylinder, a third piston may be coupled to the third crank pin andlocated in the third cylinder, and a fourth piston may be coupled to thefourth crank pin and located in the fourth cylinder. The engine assemblymay define a firing order including the second cylinder and the thirdcylinder having combustion events at the same time.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustrative purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a schematic illustration of an engine assembly according tothe present disclosure;

FIG. 2 is a schematic section view of the engine assembly of FIG. 1;

FIG. 3 is a side view of a crankshaft included in the engine assembly ofFIG. 1; and

FIG. 4 is a schematic illustration of crank pin orientation on thecrankshaft of FIG. 3.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Examples of the present disclosure will now be described more fully withreference to the accompanying drawings. The following description ismerely exemplary in nature and is not intended to limit the presentdisclosure, application, or uses.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

When an element or layer is referred to as being “on,” “engaged to,”“connected to” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to” or “directly coupled to” another element orlayer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

An engine assembly 10 is illustrated in FIGS. 1 and 2 and may include anengine structure 12, first, second, third and fourth pistons 14, 16, 18,20, a valvetrain assembly 22 and a crankshaft 24. The engine structure12 may include an engine block 26, a first cylinder head 28 and a secondcylinder head 30. The engine structure 12 may define first, second,third and fourth cylinders 32, 34, 36, 38 in the engine block 26. In thepresent non-limiting example, the engine block 26 includes a first bankof cylinders 40 defining two cylinders and a second bank of cylinders 42defining two cylinders.

The first and third cylinders 32, 36 may be defined in the first bank 40and the second and fourth cylinders 34, 38 may be defined in the secondbank 42. A bank angle (α_(B)) may be defined between the first andsecond banks of cylinders 40, 42 forming a V4 arrangement. The firstpiston 14 may be located in the first cylinder 32, the second piston 16may be located in the second cylinder 34, the third piston 18 may belocated in the third cylinder 36, and the fourth piston 20 may belocated in the fourth cylinder 38.

As seen in FIG. 2, the first cylinder head 28 may define intake ports 44and exhaust ports 46 in communication with the first and third cylinders32, 36. Similarly, the second cylinder head 30 may define intake ports48 and exhaust ports 50 in communication with the second and fourthcylinders 34, 38. The section view illustrated in FIG. 2 includes thefirst and second cylinders 32, 34. For simplicity, the port arrangementand valvetrain corresponding to the third and fourth cylinders 36, 38will not be described in detail with the understanding that thedescription relative to the first and second cylinders 32, 34 appliesequally as indicated below.

The valvetrain assembly 22 may include intake valves 52 located in theintake ports 44, 48 and exhaust valves 54 located in the exhaust ports46, 50, first, second, third and fourth valve lift mechanisms 56, 58,60, 62 and camshafts 64, 66, 68, 70. While illustrated as an overheadcam arrangement, it is understood that the present disclosure is notlimited to overhead cam arrangements and applies equally to a variety ofother engine configurations including, but not limited to, cam-in-block(or pushrod) arrangements.

The first camshaft 64 may be engaged with the first valve lift mechanism56 to displace the intake valve 52 between open and closed positions,the second camshaft 66 may be engaged with the second valve liftmechanism 58 to displace the exhaust valve 54 between open and closedpositions, the third camshaft 68 may be engaged with the third valvelift mechanism 60 to displace the intake valve 52 between open andclosed positions, and the fourth camshaft 70 may be engaged with thefourth valve lift mechanism 62 to displace the exhaust valve 54 betweenopen and closed positions.

In the present non-limiting example, the third valve lift mechanism 60may be operable in a first mode and a second mode. More specifically,the third valve lift mechanism 60 may include a first member 72 engagedwith the intake valve 52 and a second member 74 engaged with the thirdcamshaft 68. In the first mode, the first and second members 72, 74 maybe fixed for displacement with one another such that the intake valve 52is displaced to an open position when a peak 76 of a cam lobe 78 on thethird camshaft 68 engages the third valve lift mechanism 60. In thesecond mode, the first and second members 72, 74 may be displaceablerelative to one another such that the intake valve 52 remains in aclosed position when the peak 76 of the cam lobe 78 engages the thirdvalve lift mechanism 60. Alternatively, the third cylinder 36 mayinclude valve lift mechanisms operable in the first and second modes.

The crankshaft 24 may be rotationally supported on the engine structure12 by the engine block 26 and may include a first crank pin 80, a secondcrank pin 82, a third crank pin 84 and a fourth crank pin 86 eachlocated radially outward from a rotational axis (A) of the crankshaft24. The first piston 14 may be coupled to the first crank pin 80, thesecond piston 16 may be coupled to the second crank pin 82, the thirdpiston 18 may be coupled to the third crank pin 84 and the fourth piston20 may be coupled to the fourth crank pin 86. The first crank pin 80 maybe located at a first axial end of the crankshaft 24 and the fourthcrank pin 86 may be located at a second axial end of the crankshaft 24.The second crank pin 82 may be located axially between the first crankpin 80 and the fourth crank pin 86. The third crank pin 84 may belocated axially between the second crank pin 82 and the fourth crank pin86.

The crankshaft 24 may include a first bearing journal 88 at the firstaxial end of the crankshaft 24, a second bearing journal 90 axiallybetween the second and third crank pins 82, 84, and a third bearingjournal 92 at the second axial end of the crankshaft 24. Therefore, theengine structure 12 may have only three main bearings rather than thefive typically used in an inline four cylinder arrangement.

The first, second, third, and fourth crank pins 80, 82, 84, 86 may berotationally offset from one another. In the present non-limitingexample, the fourth crank pin 86 is rotationally offset from the firstcrank pin 80 by a first angle (α₁) of less than two hundred and seventydegrees in a rotational direction (R) of the crankshaft 24. The secondcrank pin 82 and the third crank pin 84 may be located rotationallybetween the first crank pin 80 and the fourth crank pin 86 in therotational direction (R) of the crankshaft 24. In the presentnon-limiting example, the first angle (α₁) is one hundred and eightydegrees.

The third crank pin 84 may be rotationally offset from the second crankpin 82 by a second angle (α₂) of less than ninety degrees in therotational direction (R) of the crankshaft 24. More specifically, thefirst, second, third, and fourth crank pins 80, 82, 84, 86 may each berotationally offset from one another by the second angle (α₂). Forexample, the second crank pin 82 may be rotationally offset from thefirst crank pin 80 by the second angle (α₂) in the rotational direction(R) of the crankshaft 24, the third crank pin 84 may be rotationallyoffset from the second crank pin 82 by the second angle (α₂) in therotational direction (R) of the crankshaft 24, and the fourth crank pin86 may be rotationally offset from the third crank pin 84 by the secondangle (α₂) in the rotational direction (R) of the crankshaft 24. Thesecond angle (α₂) may be equal to the bank angle (α_(B)). In the presentnon-limiting example, the bank angle (α_(B)) and the second angle (α₂)are each sixty degrees.

The arrangement of the crankshaft 24 may generally provide for primarybalance in the engine assembly 10 through the use of crankshaftcounterweighting and without the use of balance shafts. Engine primarybalance is achieved when the forces and moments occurring at the firstharmonic of crankshaft rotation created by the crankshaft, connectingrod and piston assembly are balanced.

The arrangement of the crankshaft 24 also provides for a common firinginterval during both engine operation including firing all fourcylinders 32, 34, 36, 38 every seven hundred and twenty degrees ofcrankshaft rotation and engine operation including only firing thefirst, third and fourth cylinders 32, 36, 38 every seven hundred andtwenty degrees of crankshaft rotation (i.e., operating the third valvelift mechanism 60 from the second cylinder 34 in the second mode). Forexample, the engine assembly 10 may define a first firing interval whenthe third valve lift mechanism 60 is operated in the first mode and asecond firing interval equal to the first firing interval when the thirdvalve lift mechanism 60 is operated in the second mode.

The first and second firing intervals may each include a combustionevent every two hundred and forty degrees of crankshaft rotation.Therefore, an even firing interval may be provided both when the thirdvalve lift mechanism 60 is operated in the first mode and when the thirdvalve lift mechanism 60 is operated in the second mode. In the presentnon-limiting example, this arrangement is made possible by firing thesecond cylinder 34 at the same time as the third cylinder 36 (i.e., thesecond cylinder 34 having a combustion event at the same time as thethird cylinder 36). The firing order may include firing the firstcylinder 32, then firing the second and third cylinders 34, 36 at thesame time, and then firing the fourth cylinder 38.

When the third valve lift mechanism 60 is operated in the first mode,the combustion cycle may include the first cylinder 32 being fired, thesecond and third cylinders 34, 36 being fired two hundred and fortydegrees of crankshaft rotation after the first cylinder 32 is fired, andthe fourth cylinder 38 being fired two hundred and forty degrees ofcrankshaft rotation after the second and third cylinders 34, 36 arefired. The cycle repeats two hundred and forty degrees of crankshaftrotation after the fourth cylinder 38 is fired.

When the third valve lift mechanism 60 is operated in the second mode,the combustion cycle may include the first cylinder 32 being fired, thethird cylinder 36 being fired (without the second cylinder 34) twohundred and forty degrees of crankshaft rotation after the firstcylinder 32 is fired, and the fourth cylinder 38 being fired two hundredand forty degrees of crankshaft rotation after the third cylinder 36 isfired. The cycle repeats two hundred and forty degrees of crankshaftrotation after the fourth cylinder 38 is fired. A similar arrangementmay be provided by firing the second cylinder 34 and not the thirdcylinder 36.

1. A V4 engine crankshaft comprising: a first crank pin defined on the crankshaft; a second crank pin defined on the crankshaft; a third crank pin defined on the crankshaft; and a fourth crank pin defined on the crankshaft and rotationally offset from the first crank pin by a first angle of less than 270 degrees in a rotational direction of the crankshaft and the second crank pin and the third crank pin being located rotationally between the first crank pin and the fourth crank pin in the rotational direction of the crankshaft.
 2. The V4 engine crankshaft of claim 1, wherein the third crank pin is rotationally offset from the second crank pin by a second angle equal to a bank angle defined between a first bank of cylinders and a second bank of cylinders defined in a V4 engine block housing the crankshaft.
 3. The V4 engine crankshaft of claim 2, wherein the third crank pin is engaged with a piston in the first bank of cylinders and the second crank pin is engaged with a piston in the second bank of cylinders.
 4. The V4 engine crankshaft of claim 3, wherein the first crank pin is located at a first axial end of the crankshaft and the fourth crank pin is located at a second axial end of the crankshaft.
 5. The V4 engine crankshaft of claim 2, wherein the second angle is less than 90 degrees.
 6. The V4 engine crankshaft of claim 1, wherein the first angle is 180 degrees.
 7. The V4 engine crankshaft of claim 6, wherein the third crank pin is rotationally offset from the second crank pin by 60 degrees.
 8. The V4 engine crankshaft of claim 1, wherein the second crank pin is located axially between the first crank pin and the fourth crank pin and the third crank pin is located axially between the second crank pin and the fourth crank pin, the second crank pin is rotationally offset from the first crank pin by 60 degrees in the rotational direction of the crankshaft, the third crank pin is rotationally offset from the second crank pin by 60 degrees in the rotational direction of the crankshaft and the fourth crank pin is rotationally offset from the third crank pin by 60 degrees in the rotational direction of the crankshaft.
 9. An engine assembly comprising: an engine structure including an engine block defining a first bank of cylinders including two cylinders and a second bank of cylinders including two cylinders forming a V4 arrangement; and a crankshaft rotationally supported on the engine structure and including a first crank pin, a second crank pin, a third crank and a fourth crank pin rotationally offset from the first crank pin by a first angle of less than 270 degrees in a rotational direction of the crankshaft, the second crank pin and the third crank pin being located rotationally between the first crank pin and the fourth crank pin in the rotational direction of the crankshaft.
 10. The engine assembly of claim 9, wherein the third crank pin is rotationally offset from the second crank pin by a second angle equal to a bank angle defined between the first bank of cylinders and the second bank of cylinders.
 11. The engine assembly of claim 10, further comprising a first piston coupled to the first crank pin and located in a first cylinder defined in the first bank of cylinders, a second piston coupled to the second crank pin and located in a second cylinder defined in the second bank of cylinders, a third piston coupled to the third crank pin and located in a third cylinder defined in the first bank of cylinders and a fourth piston coupled to the fourth crank pin and located in a fourth cylinder defined in the second bank of cylinders.
 12. The engine assembly of claim 11, wherein the first crank pin is located at a first axial end of the crankshaft and the fourth crank pin is located at a second axial end of the crankshaft.
 13. The engine assembly of claim 10, wherein the second angle is less than 90 degrees.
 14. The engine assembly of claim 9, further comprising a first piston coupled to the first crank pin and located in a first cylinder defined in the first bank of cylinders, a second piston coupled to the second crank pin and located in a second cylinder defined in the second bank of cylinders, a third piston coupled to the third crank pin and located in a third cylinder defined in the first bank of cylinders and a fourth piston coupled to the fourth crank pin and located in a fourth cylinder defined in the second bank of cylinders, the engine assembly defining a firing order including the second cylinder and the third cylinder having a combustion event at the same time.
 15. The engine assembly of claim 14, further comprising a cylinder head located on the engine block and defining a port in communication with the second cylinder, a valve located within the port, a valve lift mechanism engaged with the valve and a camshaft engaged with the valve lift mechanism, the valve lift mechanism being operable in a first mode and a second mode, the first mode including the valve being displaced to an open position when the valve lift mechanism is engaged by a peak of a cam lobe on the camshaft and the second mode including the valve remaining in a closed position when the valve lift mechanism is engaged by the peak of the cam lobe.
 16. The engine assembly of claim 15, wherein the engine assembly defines a first firing interval when the valve lift mechanism is operated in the first mode and a second firing interval equal to the first firing interval when the valve lift mechanism is operated in the second mode.
 17. The engine assembly of claim 9, wherein the first angle is 180 degrees.
 18. The engine assembly of claim 17, wherein the third crank pin is rotationally offset from the second crank pin by 60 degrees.
 19. The engine assembly of claim 9, wherein the second crank pin is located axially between the first crank pin and the fourth crank pin and the third crank pin is located axially between the second crank pin and the fourth crank pin, the second crank pin is rotationally offset from the first crank pin by 60 degrees in the rotational direction of the crankshaft, the third crank pin is rotationally offset from the second crank pin by 60 degrees in the rotational direction of the crankshaft and the fourth crank pin is rotationally offset from the third crank pin by 60 degrees in the rotational direction of the crankshaft.
 20. An engine assembly comprising: an engine structure including an engine block defining a first bank of cylinders including two cylinders and a second bank of cylinders including two cylinders forming a V4 arrangement having a bank angle of 60 degrees; a crankshaft rotationally supported on the engine structure and including a first crank pin, a second crank pin rotationally offset from the first crank pin in a rotational direction of the crankshaft by 60 degrees, a third crank pin rotationally offset from the second crank pin in the rotational direction by 60 degrees, and a fourth crank pin rotationally offset from the third crank pin in the rotational direction by 60 degrees; and a first piston coupled to the first crank pin and located in a first cylinder defined in the first bank of cylinders, a second piston coupled to the second crank pin and located in a second cylinder defined in the second bank of cylinders, a third piston coupled to the third crank pin and located in a third cylinder defined in the first bank of cylinders, and a fourth piston coupled to the fourth crank pin and located in a fourth cylinder defined in the second bank of cylinders, the engine assembly defining a firing order including the second cylinder and the third cylinder having combustion events at the same time. 